In comparison with electrophotographic materials and the like, silver halide color photographic materials are excellent in high-intensity recording ability. In addition, they are easily handled and are inexpensive. Owing to these features, silver halide color photographic materials are widely used in many fields. One performance of silver halide color photographic materials that is desired to be improved further, however, is the capacity for rapid processing. Also desired and important is the performance capacity to offer users prints of stable quality.
One means of attaining rapid processing ability is to make the content of silver chloride high. Methods wherein an emulsion having a high silver chloride content is used are described, for example, in JP-A ("JP-A" means unexamined published Japanese patent application) Nos. 95345/1983, 232342/1984, and 19140/1985. Also, in the actual marketplace, the content of silver chloride in emulsions used in photographic materials is rapidly being made high.
From the outset of study on the development of photographic materials containing a high-silver-chloride emulsion, it was known that there were such defects as that when a high-silver-chloride emulsion is used, in comparison with conventional high-silver-bromide emulsions, the high-silver-chloride emulsion is hard to give a high sensitivity by usual chemical sensitization. Further, it was known that the reciprocity law failure, in particular, the change in sensitivity and gradation at the time when the photographic material of high-silver-chloride emulsion is exposed to light under high intensity conditions is great. In order to overcome these, various techniques have been developed.
On the other hand, for example, in recent years it is desired to carry out the exposure to light in a short period of time, in order to improve the productivity of photofinishing labs. Further, increasingly images are being formed by the so-called scanner system, wherein an original picture is scanned and, based on its image signal, a photographic material is exposed to high-intensity light for a short period of time, to form an image corresponding to the original image. Consequently, there is increasing demand that, when a photographic material made of a high-silver-chloride emulsion is exposed to high-intensity light for a short period of time, the change in photographic properties is made smaller.
One known method of making the sensitivity of high-silver-chloride emulsions high, or of improving other performance thereof, is to dope the emulsion grains with metal ions. For example, JP-A No. 20853/1990 discloses that, by doping a high-silver-chloride emulsion with a hexacoordinate complex of Re or Os having at least four cyan ligands, high sensitivity is attained. JP-A No. 105940/1989 discloses that a high-silver-chloride emulsion having silver-bromide-rich regions doped selectively with iridium can give an emulsion excellent in reciprocity characteristics without impairing the latent-image stability within a few hours after exposure to light. JP-A No. 132647/1991 discloses that a high-silver-chloride emulsion containing iron ions can give high sensitivity and hard gradation; it can reduce the change in sensitivity due to a change in illumination intensity or in temperature at the time of exposure to light; and it can decrease the desensitization that will be caused by pressure. JP-A Nos. 9034/1992 and 9035/1992 disclose that a high-silver-chloride emulsion containing a specific metal complex with at least 2 cyan ligands can give high sensitivity; it is small in reciprocity law failure and good in latent-image stability; and it can reduce pressure marks. Further, JP-A No. 18548/1990 discloses that, by doping with ions of metals of Group VIII of the Periodic Table, or transition metals of Group II of the Periodic Table, or lead or thallium ions, the change in photographic properties due to multiple exposures that will occur at the time of high-intensity exposure can be reduced.
According to study made by the present inventors, the doping with metal ions described in JP-A No. 18548/1990 improves high-intensity failure and also improves latent-image stability immediately after the production of the photographic material. However, study of the latent-image stability of this photographic material after raw stock storage has revealed the defect that remarkable sensitization occurs after storage of the latent image.